Conserving power is particularly important in portable communication receivers which are typically powered by battery power or other depletable power source. Typically, an information distribution system periodically transmits large amounts of information to distributed communication receivers. The large volume of transmitted information per transmission batch and the large number of transmissions over time can require the communication receivers to receive and process the transmitted information and consequently consume power most of the time. This can seriously reduce the battery life of the communication receivers. Short battery life normally equates to requiring the users of the communication receivers to replenish the batteries or other depletable power source in the communication receivers more often than would reasonably be acceptable by the users. Besides the detrimental economic impact and the inconvenience of replacing the power source affecting the users, the added waste of the depleted batteries can be an environmentally unacceptable byproduct.
Generally, the communication receiver receives the transmitted information, determines whether the communication receiver has subscribed to the particular transmitted information, and then, if subscribed to, stores the transmitted information into a memory for subsequent retrieval by a user of the communication receiver. For example, a distributed population of paging receivers may subscribe to one or more different information categories, e.g., weather, stock, sports, news, etc., from a very large selection, and possibly from more than one information service provider. Each one of the many subscription categories of the information service provider typically is uniquely identifiable to the subscribing paging receivers. Each paging receiver can selectively "detect" only the "subscribed to" information message, e.g., by detecting an address coupled with the transmitted information. The paging receiver attempts to conserve power and extend battery life by turning off unnecessary electronic circuits when the information message is not destined for the particular paging receiver. This continuous process of receiving information and determining whether the communication receiver subscribed to the particular transmitted information can rapidly deplete the power of a power source, e.g., a battery, because more often than not the communication receiver is.
Although a number of battery saving techniques have been utilized to generally conserve power in communication receivers while detecting an address of a transmission, information distribution communication systems have specific requirements that tend to conflict with the goal of maximizing power conservation. For example, each communication receiver may want to subscribe to a large number of information subscriptions from one or more information service providers. Further, for transmission efficiency, each information subscription may be embedded in a larger information transmission batch, where each information subscription is identified by an address also embedded in the batch. All the communication receivers subscribing to a particular information subscription must search for the particular subscription address to detect the transmission of the information subscription. While searching for the particular address in large information transmission batches that are being periodically transmitted the communication receivers can consume significant amounts of power from their power sources.
For example, one approach has been to include sub-addressing information in a data portion of a long transmitted message. That is, a communication receiver would detect an address in the message, such as to identify the general information service provider, and subsequently would search the length of a long data portion of the message to identify whether any subscriptions are transmitted within the transmission. These subscriptions comprised sub-addresses followed by corresponding information data for each sub-address, all within the data portion of the message. One communication system of the general type discussed above is disclosed in International Application Number PCT/US88/01581, which was published on Nov. 17, 1988 having the International Publication Number WO 88/09104, by the inventors Fascenda et al.
This approach has experienced the significant drawback of requiring the distributed communication receivers to search, and consequently stay ON for, the data portion of the message even if the message had no subscriptions for the particular communication receiver. Therefore, battery life has suffered in those communication receivers subscribing to the information service provider.
An alternative approach can be to provide many different addresses to the general information service provider, one address for each of the many subscriptions in the service. Unfortunately, conventional communication receivers subscribing to anything more than a small number of subscriptions would be overwhelmed by the processing power required to decode all the potential addresses corresponding to their subscriptions.
Therefore, this addressing limitation can pose a severe limitation to the information service provider attempting to provide a rich selection of services for customers. The necessity for maximizing the availability of subscriptions and services to potential customers is obvious in today's competitive marketplace.
Thus, there is a need to provide a distributed information communication system enabling communication receivers to selectively receive large numbers of information subscriptions while conserving power at the communication receiver.